1. Technical Field
This invention pertains in part to the art of visual communication of symbols and pictures by means of a modulated array of discrete light producing elements which array is smaller in number than the number of elements in the visual scene to be communicated. Also, this invention pertains in part to the art of tachistoscopy wherein visual images are flashed for brief intervals in the field of view of an observer or test subject. And in addition, this invention pertains to the art of creating a visual illusion, wherein the observer perceives images as originating from locations where there is no apparent source.
2. Background Art
Signs, data displays and pictoral displays using discrete light producing elements in an n.times.m array and modulated in intensity to form letters and pictures that are stationary or that move are well known.
A switching light source such as light emitting diodes, cathode ray tube phosphors, and gas discharge tubes permitted the invention of synthetic n.times.m arrays wherein a smaller number of light sources are made to move by mechanical means or to apparently move by mechanical and optical means, or by electromagnetic deflector means, and so to produce light in successive segments from n.times.m locations, the motion/apparent motion and modulating means being done quickly and repetetively so that the well known persistance characteristic of the eye causes the observer to see a complete, steady and constant image, provided he fixes his gaze on the area where the synthetic display is being generated, and provided the scanning means is synchronised to the light modulating means. See for example U.S. Pat. No. 4,099,172, Montanari et al.
The present invention departs from the prior art in that means for moving the light producing elements are omitted from the display device. Instead, the array is fixed in space and modulated in a manner attuned to characteristic scanning motions of the human eye, so that the information is perceived for a short interval after the observers eyes are in motion relative to the array during which interval the eye is normally unreceptive to visual information. This technique achieves an unusual illusory effect of producing a momentary perceptible image in a space dissociated from the actual array of light producing elements.
Although the present invention is simpler than the prior art in that scanning means are obviated and therefore smaller sizes can be achieved; the resultant visual effect is sufficiently different, having new and different applications, so that it is in a class apart from the prior art.